Demi MooreI'M DIVORCING ASHTONCheating Scandal to Blame

11/17/2011 1:28 PM PST

Demi Moore To Divorce Ashton Kutcher

Demi Moore will divorce Ashton Kutcher, her husband of 6 years ... and she's strongly suggesting it's because of the cheating scandal.

The 49-year-old Moore says she's ending her marriage "with great sadness and a heavy heart."

Demi says, "as a woman, a mother and a wife, there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life."

Ashton just tweeted, "I will forever cherish the time I spent with Demi. Marriage is one of the most difficult things in the world and unfortunately sometimes they fail" -- though it's unclear if this message was approved by his Twitter team.

Demi and Ashton made headlines in September after a 22-year-old woman named Sara Leal claimed she had unprotected sex with him in San Diego.

Leal claimed Ashton told her he was "separated" from Demi at the time of the alleged affair.